Large-conductance calcium-activated potassium channels in neonatal rat intracardiac ganglion neurons
RIS ID
106095
Abstract
The properties of single Ca2+-activated K+ (BK) channels in neonatal rat intracardiac neurons were investigated using the patch-clamp recording technique. In symmetrical 140 mM K+. the single-channel slope conductance was linear in the voltage range -60/+60 mV, and was 207±19 pS. Na+ ions were not measurably permeant through the open channel. Channel activity increased with the cytoplasmic free Ca2+ concentration ([Ca2+]i) with a Hill plot giving a half-saturating [Ca2+] (K0.5) of 1.35 μM and slope of ≅3. The BK channel was inhibited reversibly by external tetraethylammonium (TEA) ions, charybdotoxin, and quinine and was resistant to block by 4-aminopyridine and apamin. Ionomycin (1-10 μM) increased BK channel activity in the cell-attached recording configuration. The resting activity was consistent with a [Ca2+]i <100 nM and the increased channel activity evoked by ionomycin was consistent with a rise in [Ca2+]i to ≥ 0.3 μM. TEA (0.2-1 mM) increased the action potential duration 1.5-fold and reduced the amplitude and duration of the afterhyperpolarization (AHP) by 26%. Charybdotoxin (100 nM) did not significantly alter the action potential duration or AHP amplitude but reduced the AHP duration by 40%. Taken together, these data indicate that BK channel activation contributes to the action potential and AHP duration in rat intracardiac neurons.
Publication Details
Franciolini, F., Hogg, R., Catacuzzeno, L., Petris, A., Trequattrini, C. & Adams, D. J. (2001). Large-conductance calcium-activated potassium channels in neonatal rat intracardiac ganglion neurons. Pfluegers Archiv: European journal of physiology, 441 (5), 629-638.